In a mobile log splitter such as, for example, the log splitter disclosed in U.S. Pat. No. 3,077,214 assigned to the assignee of the present invention, an elongated rigid frame has one end portion supporting a wedge-shaped splitting element or wedge, and a hydraulic cylinder is secured to the opposite end portion of the frame. The cylinder has a piston rod which connects with a ram supported by the frame for linear movement in opposing relation to the splitting element or wedge.
A hydraulic fluid storage tank or reservoir is secured to the end portion of the frame which carries the hydraulic cylinder and is supported by an axle which carries a pair of wheels to provide for transporting the log splitter. The reservoir or tank also supports a gasoline engine which drives a hydraulic pump, and the pump supplies hydraulic fluid at a high pressure to the hydraulic cylinder when it is desired to extend the ram for splitting a log.
When a single acting hydraulic cylinder is used on a log splitter to reduce the manufacturing costs, the piston rod and ram are usually returned to the retracted position by a cable connected to a tension spring. The hydraulic supply line extending from the pump to the cylinder is connected to the fluid reservoir through a line having a high pressure relief valve which is selected or set according to the pressure necessary within the hydraulic cylinder to perform the log splitting operation. The hydraulic supply line is also connected to the reservoir by a return line having a control valve which is opened when it is desired to retract the ram so that the fluid in the cylinder returns to the reservoir through the control valve.
It has been found desirable to provide for rapidly returning the ram and the piston rod after splitting a log so that another log may be loaded onto the splitter and split as soon as possible. However, the flow rate of hydraulic fluid from the cylinder back to the reservoir is limited by the size of the control valve which must also be constructed to withstand the high pressure of the fluid pumped into the cylinder during extension of the ram and splitting of a log. If a large control valve is used to provide for a more rapid return for the ram, the cost of the control valve becomes excessive and substantially increases the cost of the log splitter.